800 NORTH AMERICAN INDEX FOSSILS. 



61 8. T. curvilirata Conrad. (Fig. 1173,(7. ) Miocenic. 

 With ribs curving backwards and slightly nodose on subsutural 



band. 



Chesapeakean of Atlantic coast. 



619. T. (Hastula) simplex Conrad. (Fig. 1173, h,i.) Miocenic. 

 With broader apical angle (broadest in var. sublirata Conrad, 



Fig. 1 173, i). Surface smooth except for curving lines of growth. 

 Chesapeakean of Atlantic coast. 



Family Pleurotomid^e Stoliczka. 



CXCIII. Pleurotoma Lamarck. 

 Fusiform shells with rather high spire, and more or less con- 

 stricted anterior canal of equal length with the spire ; whorls var- 

 iously ornamented with ribs and spirals, rarely smooth ; outer lip 

 with a notch or more or less deep slit, generally on the shoulder 

 angle; columella smooth; operculum horny, with apical nucleus. 

 Cretacic-Recent. 



(This group contains a large number of distinct genetic series, 

 which include many distinct genera.) 



620. P. (Surcula) persa Whitfield. (Fig. 1174.) Eocenic. 

 Volutions rounded below but with concave shoulder, embracing 



to lower side of rounded angle which is prominent above the 



Fig. 1 1 74. Surcula persa. Fig. 1175. Surcula ostrarupis. 



(After Harris. ) (After Harris. ) 



suture; notch broad on the shoulder; surface marked only by 

 spirals and lines of growth. 

 Midwayan of Alabama. 



621. P. (Surcula) ostrarupis Harris. (Fig. 1175.) Eocenic. 

 Broader than preceding, with shorter, more curved canal, more 



